1. Field of the Invention
The present invention is concerned with improved reactor screen apparatus especially useful in conjunction with an oil shale reactor of the type described in U.S. Pat. No. 4,088,562. More particularly, it is concerned with such a reactor screen which is characterized by provision of a plurality of shale-receiving concavities especially designed to facilitate even gas flow through the shale pile and rapid, gravity-induced emptying of the reactor when the recoverable hydrocarbons have been removed from the shale. It is also contemplated that the screen hereof will be useful in other manufacturing and recovery processes.
2. Description of the Prior Art
U.S. Pat. No. 4,088,562 describes a major breakthrough in the art of oil shale processing. As an adjunct of this process, a batch-type reactor is employed wherein a charge of shale is suspended in a substantially stationary condition while hot, oxygen-free gases are passed therethrough. Within the reactor, the charge of shale is supported upon a gas-pervious, perforate screen. In practice, hot gases are passed upwardly through a central riser, and thence are directed downwardly through the shale pile for passage through the screen and ultimate transfer to a furnace for reheating thereof.
In view of the relationship between the invention herein described and claimed and U.S. Pat. No. 4,088,562, the latter patent is hereby expressly incorporated by reference into this specification.
It will be readily appreciated that large scale commercial operations in accordance with U.S. Pat. No. 4,088,562 require one or more large reactors (at present reactors capable of holding 60 and 120 ton charges of shale are contemplated), and accordingly the shale-supporting screens thereof must be engineered from the standpoint of several important operational characteristics. For example, with such large masses of shale it is important that an adequate and even flow of heating gases be provided, and that channeling of gas flow through the pile is avoided. Furthermore, shale rock used in the process is in the form of irregularly shaped pieces which, after the heating step, are very hot. Accordingly, manual handling of such rock is absolutely precluded, even if this were viable from a commercial standpoint. As a consequence, the reactor and associated shale-supporting screen must be constructed so as to ensure smooth material flow of hot shale without plugging of the system. Finally, it will be readily understood that a screen selected for use in a shale oil reactor must be sufficiently strong to withstand the weight of the shale and the rather severe operating conditions encountered.